The present invention relates to a method of an electronic engine control for an internal combustion engine having a plurality of cylinders, in particular relates to an electronic ignition timing control of an internal combustion engine in association with an electronic fuel injection control suitable for an automobile gasoline engine having a plurality of cylinders.
Automobile engines, in particular automobile gasoline engines are required to overcome sever exhaust gas regulations as well as to achieve a further higher performance, for this reasons such engine control devices are currently used wherein several kinds of data are taken in representing the engine operating conditions such as intake air flow and rotating speed of the engine, predetermined control data for the respective cylinders are calculated based upon these data and the amount of fuel to be fed and the ignition timing therefore are separately controlled for every cylinder in response to these control data.
In such engine control devices the several kinds of data representing the engine operating conditions are taken in and renewed one after another along with the passage of time and the amount of fuel to be injected and the ignition timing for the respective cylinders are calculated one after another based upon the newest data renewed in such a manner.
JP-A-60-156952 (1985) discloses an air fuel ratio control device for reducing engine torque fluctuation to improve engine operating property wherein the ignition timing is retarded or advanced in response to rich or lean state of the air fuel ratio with respect to a target air fuel ratio determining an optimum ignition timing. In this device the correction of the ignition timing is also carried out based upon the newest air fuel ratio feed back coefficient renewed one after another along with the passage of time.
In the conventional air fuel ratio control device, the newest air fuel ratio feed back coefficient is always used for correcting an ignition time for every cylinder and no particular consideration is not made in connection with which air fuel ratio feed back coefficients are to be used for correcting an ignition timing for a specific cylinder, such that an insufficient suppression of engine torque fluctuation is considered to be achieved.
In consideration of the above problems in the conventional art, an object of the present invention is to provided a method of an electronic engine control for an internal combustion engine having a plurality of cylinders which effectively suppresses the engine torque fluctuation during the air fuel ratio feed back control.
According to the present invention, an air fuel ratio feed back coefficient obtained at a predetermined sequential timing which is used for calculating amount of fuel to be injected to a specific cylinder is also used for correcting timing of ignition for the same cylinder which follows immediately after the calculated amount of fuel has been injected into the specific cylinder.
In the method of an electronic engine control for an internal combustion engine having a plurality of cylinders according to the present invention, with the very same air fuel ratio feed back coefficient which has been used for calculating the fuel injection amount to a specific cylinder, the ignition timing for the same cylinder which follows immediately after the fuel injection of the calculated amount of fuel into the specific cylinder is corrected. As a result, use of different air fuel ratio feed back coefficients for the determination of amount of fuel to be injected to the specific cylinder and of the ignition timing for the injected fuel for the same cylinder due to difference between the fuel injection timing and the ignition timing is eliminated, thereby an optimum ignition timing correction is performed which meets the air fuel ratio of the specific cylinder.
Since, as explained above, the very same air fuel ratio feed back coefficient obtained at a predetermined sequential timing which has been used for calculating the amount of fuel to be injected to the specific cylinder is also used for correcting the timing of ignition for the same cylinder which follows immediately after the calculated amount of fuel has been injected into the specific cylinder, the engine torque fluctuation is effectively suppressed, stability during idling operation is improved occurrence of the surge during a low speed running is prevented.